Thanks for the replies guy's........yes i don't think it has been a common thing to reunite an engine and gearbox. It is probably far too much work to carry out unless the engine is a rare one or you are able to carry out the repairs yourself. My thoughts are that you really need to jig the crankcase and gear box half as a pair and be able to get to the inside and outside.........If you did it this way, I feel the distortion would possibly be less, as you could alternate the welding from the inside and outside a bit at a time. I have 3 chopped crankcases, one original gearbox.......one of the cases is a genuine series "B" Shadow engine.........it is the one where the entire section of the inner primary housing has been cut off........this is the case we want to reunite with the gearbox.